Versatile compact air precleaner, air cleaning method and disposable air filter cartridge for air precleaner

ABSTRACT

A versatile compact air precleaner, air cleaning method and disposable air filter cartridge for air precleaner for separating heavier-than-air particulate debris from debris laden air to provide a clean airflow, wherein a flow path for air passing through a separator chamber of the air precleaner is retroflexed en route to the outlet. A plurality of independently rotatably adjustable housing sections of a housing provide utility with multiple clean air outlet configurations, freedom of direction of ejection of particulate debris from the ejector ports, different inlet configurations, mounting of the precleaner from different sides, accommodation of different sizes of filters, and different clean airflow rate capabilities. A separator chamber end section including the ejector ports is connected to the filter as a removable, disposable air filter cartridge to obviate ejector port clogging with change of filters.

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 of provisionalapplication No. 61/513,201 filed Jul. 29, 2011. The entire disclosure ofprovisional application No. 61/513,201 is incorporated herein byreference.

TECHNICAL FIELD

The present invention is directed to an improved air precleaner, aircleaning method and disposable air filter cartridge for air precleanerfor efficiently removing heavier-than-air particulate debris from debrisladen air to provide a clean airflow to a device with which it is used.The air precleaner is versatile and compact for use in limited spaceapplications having different configurations and clean airflow rateperformance requirements in total airflow applications such asventilation systems, as a fixed airflow provider for heat exchangers andheating and air conditioning systems, and with devices having a variableairflow demand, particularly internal combustion engines which exert avariable vacuum in their air intake to be supplied with clean air. Theinvention according to a preferred embodiment represents an improvementto the air precleaner and method disclosed in commonly owned U.S. patentapplication Ser. No. 11/877,036 filed Oct. 23, 2007, now U.S. Pat. No.8,007,565 issued Aug. 30, 2011, the entire disclosure of which isincorporated herein by reference.

BACKGROUND AND SUMMARY

Air precleaners and methods that centrifugally separate heavier-than-airparticles from the air to be used in internal combustion engines,ventilation systems, and other apparatus that draw in air laden withdebris, are known. These include powered air precleaners which employ amotor-driven fan for drawing debris laden air into the air precleaner aswell as air precleaners which rely solely upon a vacuum applied to theprecleaner by the device being supplied with clean air, such as aninternal combustion engine, for drawing debris laden air into theprecleaner. The known air precleaners can include a filter, and/or beused in combination with a device downstream of the clean air outlet ofthe precleaner having a filter, for removing additional debris from theair. Examples of assignee's prior air precleaners are shown in U.S. Pat.Nos.:

U.S. Pat. No. 5,656,050

U.S. Pat. No. 5,766,315

U.S. Pat. No. 6,319,304

U.S. Pat. No. 6,338,745

U.S. Pat. No. 6,406,506

U.S. Pat. No. 6,425,943

U.S. Pat. No. 6,878,189

U.S. Pat. No. 7,056,368

U.S. Pat. No. 7,452,409.

Drawbacks of the known air precleaners include that they can be too bigfor limited space applications and they can require custom manufacturingof an individual air precleaner for a particular application due tovariations in configuration and performance requirements. This limitsthe applications of the air precleaners and adversely effects the timeand cost for their manufacture. Examples of air precleaner variationsbetween applications which require individual customization include therequired direction of ejection of centrifugally separated particulatedebris from the precleaner to atmosphere, the orientation of the cleanair outlet for providing clean air from the precleaner to the devicewith which it is used, the size of a filter in the device, the locationof the available supporting structure for mounting the air precleaner,and the clean airflow rate required from the precleaner. In the case ofpowered air precleaners, the life of the motor of the motor-driven fanin the precleaner has been found to be reduced due to debris/dirtbuildup on the motor which lowers the cooling thereof. Further, it hasbeen found that the ejection ports for ejecting debris laden aircentrifugally separated from the rotating airflow in the air precleanerare subject to being clogged thereby lowering operational efficiency anddecreasing filter life.

There is a need for an improved air precleaner and air cleaning methodwhich overcome these drawbacks and limitations of the known airprecleaners. More particularly, there is a need for an improved airprecleaner that is compact permitting its use in limited spaceapplications, and is versatile for use in applications with differentconfigurations and clean airflow rate requirements thereby obviating thenecessity of a complete custom manufacturing of an individual airprecleaner for each application and reducing the time and expense ofmanufacturing. There is a need for a powered air precleaner which canextend the motor life of a motor driven fan therein. There is also aneed for an improved air precleaner and air cleaning method which willfacilitate restoring the precleaner to its full operating potential inthe event the ejector ports of the precleaner have become clogged.

The improved versatile compact air precleaner, air cleaning method anddisposable air filter cartridge of the present invention address theseneeds. The versatile compact air precleaner of the invention forseparating heavier-than-air particulate debris from debris laden air toprovide a clean airflow in accordance with a disclosed embodimentcomprises a flow path extending through the precleaner from an inlet toan outlet, a motor-driven fan with a fan blade to draw particulatedebris laden air into the inlet and flow the debris laden air along theflow path, and an airflow management structure positioned along the flowpath to rotate debris laden air drawn into an inlet about an axis toform a rotating flow that stratifies the debris laden air with theheaviest particles in the outermost orbits of the rotating flow. Aseparator chamber in the flow path centrifugally separates and removesparticulate debris laden air from the rotating flow. At least oneejector port is provided through which particulate debris laden air isejected from the rotating flow in the separator chamber. The flow pathfor air passing through the separator chamber is retroflexed en route tothe outlet. The precleaner of the disclosed embodiment is elongated inthe direction of the axis with the inlet and the at least one ejectorport located at opposite ends and the outlet located intermediate theends. By retroflexing the flow path in this manner the air precleaner ismore compact permitting use in applications with limited space.

Connection of the air precleaner to a supporting structure/device isfacilitated by the provision of at least one mount on the precleaner formounting the precleaner on the support/device. Versatility is improvedfor using the device in various configurations in that the airprecleaner has means for independently adjusting a radial position ofeach of the outlet, the at least one ejector port and the at least onemount about the axis of the precleaner to configure the precleaner formounting on the device and connection to the inlet thereof. In thedisclosed embodiment, the means for independently adjusting a radialposition includes a housing having a plurality of housing sectionsarranged sequentially along the axis of the air precleaner and means forreleasably connecting and adjustably rotating the sections with respectto one another about the axis. The inlet is located on a housing sectionapart from that of the at least one ejector port and the outlet and isreleasably connected to the precleaner. Accordingly, the inletconfiguration can be readily changed permitting adaptation of the airprecleaner for ingress of air directly from the atmosphere or indirectlyfrom an air supply conduit connected to the inlet. The adjustabilityafforded by these features allows the use of a single air precleaner inmany different applications/configurations and also facilitates, withonly minimal changes, the use of different sizes of filters within theair precleaner and changeover of the air precleaner to meet differentairflow rate requirements.

The disclosed, preferred embodiment of the air precleaner of theinvention comprises a motor-driven fan with a fan blade mounted on anoutput shaft of a motor. The fan blade is located in the flow pathupstream of the separator chamber and draws particulate debris laden airinto the inlet and flows the debris laden air along the flow path. Themotor-driven fan is supported on a shroud of the airflow managementstructure. The shroud tapers outwardly with respect to the axisdownstream of the fan blade and shields the motor of the motor-drivenfan from the incoming air. A plurality of stationary vanes of theairflow management structure rotate the incoming debris laden air aboutthe axis, compressing the volume of debris laden air to increase the airvelocity and centrifugal force acting on the airborne particles. Themotor of the motor-driven fan beneath the shroud is in the flow pathdownstream of the separator chamber, which advantageously reduces dirtand debris buildup on the motor for improved cooling and longer motorlife.

The air precleaner of the embodiment further comprises an air filterwhich forms an inner wall of the separator chamber for filtering airfrom the innermost orbits of the rotating flow. The flow path for airthrough the separator chamber is retroflexed en route to the outletafter passing through the filter. The filter is tubular, preferablycylindrical and has a longitudinally extending internal passage forflowing filtered air from the separator chamber toward an outlet of theair precleaner.

The separator chamber includes a separator chamber end section whichincludes the at least one ejector port. The separator chamber endsection is connected to one end of the air filter and is, together withthe air filter, removably connected with the air precleaner as adisposable air filter cartridge. Thus, the ejection ports are thrownaway with the filter at filter change thereby restoring the airprecleaner to its full operating potential if the ports have beenclogged during the past filter cycle.

An air cleaning method of the present invention comprises drawingheaver-than-air particulate debris laden air into an inlet of an airprecleaner, flowing the particulate debris laden air along the flow pathin the precleaner, rotating the flow of the debris laden air about anaxis in the precleaner to form a stratified rotating flow with theheaviest particles in the outermost orbits of the rotating flow,ejecting particulate debris laden air from the outermost orbits of thestratified rotating flow through at least one ejector port of theprecleaner, filtering air from the innermost orbits of the stratifiedrotating flow through an air filter extending along said axis within therotating flow, flowing the filtered air along the flow path toward anoutlet of the air precleaner, including utilizing a removable,disposable air filter cartridge in the air precleaner wherein the airfilter and the at least one ejector port are integral parts of theremovable, disposable air filter cartridge. In accordance with themethod, the filtered air leaving the air filter is flowed past the motorof the motor driven fan en route to the outlet of the air precleaner.

A disposable air filter cartridge according to the invention for use inan air precleaner as part of a separator chamber wherein particulatedebris laden air is centrifugally separated and removed from a rotatingflow of debris laden air through at least one ejector port locatedwithin a wall of the separator chamber, comprises a tubular air filterfor forming an inner wall of the separator chamber in the air precleanerand filtering air from the innermost orbits of a rotating flow of debrisladen air in the separator chamber, the tubular air filter having alongitudinally extending internal passage for flowing filtered air fromthe separator chamber toward an outlet of the air precleaner, aseparator chamber end section securely connected to one end of thetubular air filter and extending radially outwardly from the filter forforming a portion of the wall of the separator chamber, at least oneejector port formed in the separator chamber end section for removal ofdebris laden air from the rotating flow in the separator chamber, andmeans permitting releasable connection of the air filter cartridge tothe air precleaner.

These and other objects, features and advantages of the presentinvention will become more apparent from the following description of apreferred embodiment in accordance with the invention when taken inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an air precleaner of an embodiment ofthe invention as seen from one side and above.

FIG. 2 is a perspective view of the air precleaner of FIG. 1 on which anoptional rain cap has been provided above the inlet.

FIG. 3 is a side view of the air precleaner of FIG. 2, shown upstanding,as seen in a direction looking into the clean air outlet.

FIG. 4 is a side view like that of FIG. 3 wherein the air precleaner hasbeen lengthened by substitution of a longer separator chamber section ofthe housing for the shorter one shown in FIG. 3 as a filter extenderallowing the use of an extended life filter, the rain cap being omittedfrom the air precleaner as in FIG. 1.

FIG. 5 is an exploded perspective view showing respective parts indisassembled relation of the air precleaners of FIGS. 3 and 4 includingthe rain cap seen in FIG. 2 and an alternative inlet configured forconnection to an air supply conduit for air to be cleaned, and analternative clean air outlet housing section wherein the motor-drivenfan has been omitted in case a vacuum applied to the clean air outlet isused exclusively to draw debris laden air into the air precleaner.

FIG. 6 is a end view of the separator chamber/ejector port end of theair precleaner schematically illustrating with the arrows B, B′ thedirection of ejection of debris laden air from two ejector ports in theouter wall of the separator chamber at the end of the precleaner.

FIG. 7 is a schematic illustration of the eight possible outletdirections/radial positions of the clean air outlet about thelongitudinally extending axis, A-A in FIG. 1, of the precleaner of theinvention.

FIG. 8 is a perspective view of the air precleaner like FIG. 1, but withthe inlet configured for connection to an air supply conduit for air tobe cleaned as seen in FIG. 5.

FIG. 9 is a perspective view of the air precleaner of FIG. 2 as seenfrom one side and above with the air filter cartridge of the precleanerremoved and an orifice/coupling member, gasket and metal screws uponwhich an end of the air filter cartridge is sealed, when installed inthe air precleaner, shown in disassembled position.

FIG. 10 is a side view of the air precleaner of FIG. 9 without the raincap and the air filter cartridge, the precleaner having been partiallycut away to show the orifice/coupling member mounted in the precleanerfor receiving an end of the air filter cartridge is sealing relationthereon.

FIG. 11 is a perspective view of the air filter cartridge with integralseparation chamber end section/cap with ejector ports therein forremovable attachment on the precleaner portion shown in FIG. 10.

FIG. 12 is a side view of the air precleaner, partially cut away to showthe air filter cartridge mounted on the end of the separator chamberwith free end of the filter being sealingly positioned against theorifice/coupling member in the precleaner, and the rain cap being shownon the precleaner.

FIG. 13 is a side view of the air precleaner, partially cut away, likeFIG. 12, but showing the use of a vaned ring in the separator chambertoward the ejector port end of the separator chamber to enhancerotational, centrifugal air flow in the chamber about the axis A-A.

DETAILED DESCRIPTION

Referring now to the drawings, the powered air precleaner 1 of thedisclosed embodiment comprises a flow path shown by the arrows B, B′ andB″ in FIGS. 1 and 6 and arrows 55 in FIG. 12 extending through thesystem from an inlet 2 to an outlet 3. A motor-driven fan 4 is locatedalong the flow path to draw particulate debris laden air into the inletand rotate it about a longitudinal axis A-A of the system to form arotating flow that stratifies the debris laden air with the heaviestparticles in the outermost orbits of the rotating flow. Ejector ports 5and 5′, FIG. 6, are provided in a separator chamber end section 35 ofthe housing 11 for ejecting particulate debris laden air, B′, from theoutermost orbits of the stratified rotating flow in the separatorchamber 19 of the air precleaner.

The powered air precleaner 1 of the illustrated embodiment is equippedwith an air inlet screen 6 and optionally a rain cap 7, FIG. 2, for anabove-the-hood or other outdoor installation on for example a motorvehicle. The underside of the rain cap is designed to aerodynamicallydirect the airflow in a pattern into the inlet with the least amount ofairflow turbulence. The rain cap has a central depending hub, 51, FIG.12, with four projections 12 thereon press fitted into respective onesof a plurality of holes 8, FIG. 1, spaced concentrically about athreaded opening 9 at the center, on axis A-A, of the open top of theair inlet screen. The rain cap is removably secured to the air inletscreen with a threaded fastener 53, FIG. 12, which extends through acentral hole 10 in the hub 51 from the cap and is secured in thethreaded opening 9 of the air inlet screen. The screen is integrallymolded with an inlet end section 31 of a housing 11 of the airprecleaner.

The rain cap 7 is spaced above the air inlet screen 6 by the centraldepending hub. The diameter of the circular rain cap is larger than thatof the air inlet screen and the outer periphery is formed with adepending annular flange 54. The flange extends toward the precleaner,but is spaced radially outwardly therefrom, to a level of the air inletscreen for shielding against rain ingress. The annular open spacebetween the outer circumference of the inlet and the flange permitsheavier, slow moving particles to fall out before entering the poweredseparating system. This reduces debris build up on the screen.

The motor-driven fan 4 has a fan blade 12, FIG. 12, mounted on an outputshaft 13 of a motor 14. The fan blade is located below the air inletscreen and along the flow path upstream of an airflow managementstructure 15 to draw particulate debris laden into the inlet and flowthe debris laden air along the flow path as shown schematically by thearrows 55 in FIG. 12. The airflow management structure includes a shroud16 on which the motor-driven fan is supported. Releasable fasteners 17such as threaded bolts with nuts connect the motor to the upper centralend of the shroud 16, FIG. 12. The shroud tapers outwardly downstream ofthe fan blade as seen in FIG. 12, leaving an outer annular passage withcircumferentially spaced, angled, stationary vanes 18 of the airflowmanagement structure connecting the shroud 16 and housing section 32.

The tapered shroud and angled stationary vanes of the airflow managementstructure compress and rotate the debris laden air drawn into the inletby the fan to form a rotating flow about the axis A-A that stratifiesthe debris laden air with the heaviest particles in the outermost orbitsof the rotating flow. The volume of the debris laden air is compressedby the airflow management structure as it moves along the flow path toincrease the air velocity and centrifugal force acting on the airborneparticles. The motor 14 of the motor-driven fan 4 is located on theopposite side of the shroud from the fan blade and in the flow path ofclean air downstream from the separator chamber 19 as depicted in FIG.12.

The separator chamber 19 of the precleaner is in the flow pathdownstream of the shroud 16 and vanes 18 to receive the rotating flowand to centrifugally separate and remove from the rotating flowparticles of debris in the outermost orbits of the rotating flow. Theseparator chamber has an outer wall 20, FIG. 12, formed by three housingsections 33, 34, and 35 FIG. 3, of the housing of the air precleaner.The separator chamber end section 35 of the housing closes the lower endof the separator chamber and supports an air filter 23. The two radiallyouter ejector ports 5, 5′ are formed in an outer annular wall portion 66of the end section 35 which forms a portion of the outer wall of theseparator chamber when the end section is secured to the air precleanerby the releasable spring clamps 28 on separator chamber section 34.During operation of the air precleaner, particulate debris laden airfrom the outermost orbits of the rotating flow in the separator chamberis ejected to the atmosphere through the ejection ports.

The tubular, preferably cylindrical air filter 23 has a longitudinallyextending internal passage 24 therethrough. One end of the filter isconnected to end section 35. The passage 24 forms a portion of the flowpath 55 for filtered air flowing to the outlet from the other, open endof the filter. The filter is sealingly connected at the one end as by anadhesive to the center of the end wall of section 35 which closes theseparation chamber and one end of passage 24. The filter is coaxial withthe axis A-A when installed in the air precleaner with the filter beinglocated centrally within the separator chamber and forming an inner wallof the separator chamber. The filter extends the full length of thechamber where the other end releasably, sealingly engages a flange oforifice/coupling member 25, FIG. 9. The member 25 is releasablyconnected to a radially inwardly directed flange 26 connected to theshroud 16 of the airflow management structure by threaded fasteners 61,FIG. 10. A sealing gasket 62, FIG. 9, is provided between the flange 26and coupling member 25. A flexible annular seal 27, FIG. 11, mounted onthe end of the air filter sealingly engages the flange of theorifice/coupling member 25 to ensure that the flow path of air from theinnermost orbits of the stratified rotating flow in the separatorchamber to the outlet 3 is through, not around, the filter. The filteredair flows through the internal passage 24 which is in open communicationwith the central orifice in the orifice/coupling member 25 and into anarea within the shroud 16 where it flows past the motor 14 of themotor-driven fan 4 and out of the outlet 3 located intermediate the endsof the air precleaner. The lower, outer end of the shroud is sealinglysecured on the annular flange 26 for separating the portions of the flowpath upstream of the separator chamber from those downstream from theseparator chamber. As a result, the flow path for air passing throughthe filter in the separator chamber to the outlet 3 is retroflexed.

The separator chamber section 33 of the housing attached to thedownstream end/bottom of the outlet section 32 of the housing 11provides a smooth transition of the rotating airflow into the separatorchamber 19. Sealing gaskets 63, FIG. 5, are used between the varioushousing sections to seal the outer housing. The airborne debris movesalong and is pressed firmly against the inside of the outer wall 20 ofthe chamber until it reaches the ejector ports 5 and 5′ at the lower endof the separator chamber 19 where it is ejected back into theenvironment as noted above. The airflow that has been stripped of mostof the debris, in the innermost orbits of the stratified rotating flowwithin the single stage separator chamber, flows through the air filter23, within the air filter internal passage 24 to the clean air outlet 3of the air precleaner and the downstream device, such as an internalcombustion engine or ventilation system, connected to the outlet.

The plurality of housing sections, e.g. the inlet section 31, the outletsection 32, and the separator chamber sections 33, 34 and 35 arearranged sequentially along the axis A-A with the sealing gaskets 63therebetween and releasably connected to one another end-to-end at aplurality of spaced circumferential locations by releasable threadedfasteners 30. Four circumferentially spaced spring clamps 28 releasablyconnect the separator chamber end section 35 to the lower end of theseparator chamber section 34 of the housing. The lower ends of thespring clamps are releasably secured about a radially outwardlyextending flange 29 at the upper end of the end section 35. By releasingthe spring fasteners, the end section with filter 23 secured thereto canbe rotated to change the direction of the ejection ports 5, 5′ to anylocation on the periphery of the air precleaner. There is full 360° offreedom for customization of the air precleaner to a specificapplication. The spring clamps 28 are also released for replacing theassembly of the air filter and separator chamber end section, whichconstitutes a removable, disposable air filter cartridge. By includingthe ejector ports 5, 5′ in the separator chamber end section 35 of theair filter cartridge, replacement of the filter restores the airprecleaner to its full operating potential if the ejector ports had beenclogged during the past filter cycle. The arrows B, B′ in FIG. 6 depictthe directions of the ejection of debris from the two ejection ports 5,5′ in the separator chamber end section 35 of the housing.

The connections between the separator chamber section 33 of the housing11 and the outlet section 32 of the housing are formed at eight pairs ofuniformly circumferentially spaced, opposing tabs 36 on the sectionsusing threaded fasteners 30 connecting adjacent pairs of tabs. Byremoving the threaded fasteners, the outlet section can be rotated aboutthe axis A-A and selectively located in any of eight possible locationsin the air precleaner with 45° indexing provided by the tab locations.The multiple outlet configurations possible are shown schematically bythe arrows in FIG. 7.

The inlet section 31 of the housing 11 and the outlet section 32 areconnected at four pairs of opposed tabs 36 uniformly spaced about theperiphery of the sections and connected by releasable threaded fasteners30. As noted above, the inlet section 31 in the embodiment of FIG. 1 canbe replaced with an inlet section 31′ shown in FIGS. 5 and 8 having afitting 37 as a coupling for an air supply conduit as where the airprecleaner is positioned below the hood of a vehicle.

The separator chamber sections 33 and 34/34′ and inlet section 31/31′ ofthe housing 11 are each formed with a pair of mounts 38 for use inmounting the air precleaner to a support or device in use. The mountsare formed integrally with their respective housing sections. Becausethe sections 33 and 34/34′ and 31/31′ are independently rotatable aboutaxis A-A with respect to one another and the air precleaner, the mountscan be positioned to a selected circumferential location spaced every45° about the periphery of the air precleaner withouteffecting/independent of the directions of the outlet and the ejectorports. The housing sections are formed of molded plastic in thedisclosed embodiment but other materials could be used.

According to a further feature of the invention, by forming theseparator chamber of the housing with an upper section 33, as shown inFIG. 3, and a lower section 34 which is intermediate the upper sectionand the separator chamber end section 35, different size filters can beaccommodated. That is, as shown in FIG. 4, the axial length of the lowersection can be changed by replacing section 34 with longer section 34′for accommodating a longer filter in the precleaner. Likewise, theorifice/coupling member 25 connected to the airflow management structureagainst which the upper end of the filter is sealed can be changed toalter the airflow restriction/airflow rate of the air precleaner. Use ofa fan blade 12 having a different blade pitch within the air precleaneralso enables with only a few changes in the air precleaner customizationof the airflow rate of the air precleaner depending upon theapplication.

The motor of the motor-driven fan 4 and the control thereof in the airprecleaner can be in accordance with the commonly owned U.S. patentapplication Ser. No. 11/877,036 referred to above. The wiring 39 for themotor extends through a resilient wire plug 40 mounted in an opening inthe outlet section 32. The centrifugal separation of heaver-than-airparticulate debris within the air precleaner is described in detail inthe referenced application. However, the air precleaner of the inventionis more compact through the use of a flow path for air passing throughthe separator chamber which is retroflexed en route to the outletlocated intermediate the ends of the air precleaner, while at the sametime permitting use of different filters within the air precleaner, andbecause of versatility of the air precleaner, permitting a single airprecleaner to be used in different applications requiring differentconfigurations for the inlet, the outlet, the ejector ports as well asdifferent arrangements for supporting/mounting the air precleaner.Servicing the air precleaner is also facilitated. In the exampleembodiment the housing 11 in FIG. 1 has a length of 16.8 inches/42.7 cm(without rain cap—18.9 inches/48.0 cm with rain cap) and the drawingsare scaled, but other sizes could be made.

While only a single embodiment, with several variations, has been shownand described in accordance with the present invention, it is understoodthat the same is not limited thereto, but is susceptible to numerouschanges and modifications as known to the skilled artisan. For example,the air precleaner of the invention need not include a motor-driven fanbut could be of the type wherein a vacuum is provided to the precleanerat its outlet from the inlet of the downstream device being suppliedwith clean air such as an internal combustion engine. In addition, avaned ring 64, FIG. 13, secured to the inner wall of separator chamberhousing section 34, could be provided at the downstream portion of theseparator chamber 19, before end section 35 and the ejector ports. Aplurality of circumferentially spaced, angled stationary vanes on thevane ring are airflow management structure to maintain the rotationalflow of debris laden air about the axis A-A and the air filter in theseparator chamber up to the ejector ports to facilitate centrifugalseparation of debris and avoid laminar flow, particularly at highairflow rates and with longer filters. Further, the air precleaner neednot include a filter within the centrifugal separator chamber. A filter,if used, could be located downstream of the air precleaner outlet. Theadvantages of compactness and versatility of the invention would beretained in such variations. Therefore, the invention is not limited tothe details shown and described therein, but covers all such changes andmodifications as are encompassed by the scope of the appended claims.

The invention claimed is:
 1. An air cleaning method comprising: drawingheavier-than-air particulate debris laden air into an inlet at a firstaxial end of a powered air precleaner comprising a motor-driven fan witha fan blade located in a flow path in the air precleaner, the airprecleaner extending along a longitudinal axis between the first axialend and a second axial end, flowing the particulate debris laden airalong the flow path in the air precleaner from the inlet to the secondaxial end where the flow path is retroflexed en route to an outletintermediate the axial ends, rotating the flow of the debris laden airabout an axis in the air precleaner to form a stratified rotating flowwith heaviest particles in outermost orbits of the stratified rotatingflow, ejecting particulate debris laden air from the outermost orbits ofthe stratified rotating flow through at least one ejector port of theair precleaner, filtering air from innermost orbits of the stratifiedrotating flow through an air filter of the air precleaner extendingalong said axis within the rotating flow, flowing the filtered airthrough an internal passage in the air filter which forms a portion ofthe retroflexed flow path toward the outlet of the air precleaner,including utilizing a removable, disposable air filter cartridge in theair precleaner, wherein the air filter for said filtering and an endsection of the air precleaner forming the second axial end thereofclosing one end of the internal passage of the air filter and includingthe at least one ejector port for said ejecting are integral parts ofthe removable, disposable air filter cartridge of the air precleaner. 2.The air cleaning method of claim 1, including flowing the filtered airen route to the outlet past a motor of the motor-driven fan of the airprecleaner.